多维时间相关单光子计数在生物医学中的应用(英文)

Multi-dimensional time-correlated single photon counting:a fast and efficient optical recording technique for biomedical spectroscopy

传统的时间相关单光子计数(Time-correlated single photon counting, TCSPC)受计数率低、一维测量和采集时间长的限制,难以在生物医学中的推广.评述TCSPC的机理和应用,指出TCSPC是探测周期光信号内的单个光子、测量光子探测时间以及构建信号周期内光子分布与时间关系的一种技术,具有多维光子采集特性,计数率近似当前可用的探测器容量.该技术可采集光子对波长和空间座标的分布,时间尺度在皮秒量级,在实验开始时可进行二次计数.多维TCSPC技术拥有近似于理想的计数效率,其时间分辨率仅受探测器渡越时间的离散限制.故TCSPC在生物医学光谱学中极具应用价值.典型应用包括,时域光学X线断层照相、记录生物系统内的瞬态现象、荧光寿命成像显微术、活细胞内荧光共振能量转移实验,以及用荧光关联谱探索染料-蛋白复合体.

Time-correlated single photon counting （TCSPC） is based on the detection of single photons of a periodic light signal, the measurement of the detection time of the photons, and the build-up of the photon distribution versus the time in the signal period. The limitations of classic TCSPC were low count rate, long acquisition time, and the fact that the technique was intrinsically one-dimensional. We have developed an advanced TCSPC technique featuring multi-dimensional photon acquisition and a count rate close to the capability of currently available detectors. The technique is able to acquire photon distributions versus wavelength, spatial coordinates, the time on the ps scale, and a second time counting from the start of the experiment. Multi-dimensional TCSPC achieves a near-ideal counting efficiency and a time resolution limited only by the transit-time-spread of the detector. The technique is therefore exceptionally useful for biomedical spectroscopy. Typical applications include time-domain optical tomography, recording of transient phenomena in biological systems, fluorescence lifetime imaging microscopy, FRET experiments in living cells, and the investigation of dye-protein complexes by fluorescence correlation spectroscopy. We demonstrate the potential of the technique for a number of selected applications.